Question

A patient presents with proptosis and restriction of eye movements and is euthyroid. What could this be from?

• A. Orbital cellulitis
• B. Orbital lymphoma
• C. Orbital pseudotumor
• D. Thyroid ophthalmopathy

Hint:

Thyroid disease is the usual cause, but the patient is euthyroid, so look for the inflammatory mimic.

Answer 1

The Correct Option is C

Clinical pearl approach. The trap in this stem is that proptosis plus restricted movements almost screams thyroid eye disease. But examiners hand you a single discriminator: the patient is euthyroid. Strip thyroid ophthalmopathy off the table on that word alone.
Now run option elimination. Orbital cellulitis needs an infective picture: fever, red swollen lids, pain and systemic upset, none of which is given. Orbital lymphoma is a painless, slowly enlarging salmon-pink lesion, not an acute restricted-movement picture. That leaves orbital pseudotumor, also called idiopathic orbital inflammatory syndrome, a non-infective inflammatory mass that produces painful proptosis with limited motility in a patient whose thyroid is normal.
So the answer that survives is orbital pseudotumor. Remember the mnemonic: euthyroid + painful restricted proptosis = pseudotumor until proved otherwise. Ref: Comprehensive Ophthalmology, A. K. Khurana, 6e, p. 335.